我正忙着将我的一个网站从5.3升级到Laravel 5.4。我注意到，在浏览当前的Github存储库时，默认字符集和排序规则已从utf8更改为utf8mb4，以便为表情符号提供支持。
我当前的数据库（MariaDB 10.0.29）目前设置为使用utf8，但我想升级它以使用utf8mb4。不幸的是，我还没有找到有关此过程的任何文档。
也许我过度思考它，但我认为改变数据库的字符集和整理需要一些工作，至少运行一些ALTER TABLE命令。
config/database.php文件中的设置就足够了吗？由于
答案 0 :(得分：6)
好吧，我已经编写了一个迁移来实现我自己的系统。
它允许您选择指定连接名称以引用默认连接以外的连接。
它使用SHOW TABLES查询从连接数据库中获取表格列表。
然后循环遍历每个表并将所有字符串/字符类型列更新为新的字符集和整理。
我已经做到这一点，因此必须提供回调以确定列是否应将其长度更改为提供的新长度。在我的实施中，长度大于191的VARCHAR和CHAR列会在上移期间更新为长度为191，并且更新长度为191的VARCHAR和CHAR列会更新反向/向下迁移时长度为255。
一旦更新了所有字符串/字符列，将运行几个查询来更改表的字符集和排序规则，将任何剩余的排序规则转换为新排序规则，然后更改默认字符集和整理表格。
最后，数据库的默认字符集和排序规则将被更改。
最初，我试图简单地将表转换为新编码，但遇到了列长度问题。在我的MySQL / MariaDB版本中使用InnoDB时，utf8mb4中的最大字符长度为191个字符，并且更改表格排序会导致错误。
我起初只想将长度更新为新长度，但我也想提供回滚功能，所以这不是一个选项，因为在反向方法中我会设置长度utf8mb4到255的列，这些列太长了，所以我也选择更改排序规则。
然后，我尝试更改varchar和char列的长度，字符集和整理时间太长，但在我的系统中，当我有多个时，这会导致错误包含此类列的列索引。显然，多列索引必须使用相同的排序规则。
重要提示就是反向/向下迁移对每个人来说都不是100％完美。我不认为在迁移时不存储有关原始列的额外信息就可以这样做。因此，我当前的反向/向下迁移实现是假设长度为191的列最初为255.
同样重要的注意事项就是这会盲目地将所有字符串/字符列的排序规则更改为新排序规则，而不管原始排序规则，因此如果有列不同的校对，它们都将被转换为新的校对，反之亦然，原件不会被保留。
<?php
use Illuminate\Database\Migrations\Migration;
class UpgradeDatabaseToUtf8mb4 extends Migration
{
/**
* Run the migrations.
*
* @return void
*/
public function up()
{
$this->changeDatabaseCharacterSetAndCollation('utf8mb4', 'utf8mb4_unicode_ci', 191, function ($column) {
return $this->isStringTypeWithLength($column) && $column['type_brackets'] > 191;
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
$this->changeDatabaseCharacterSetAndCollation('utf8', 'utf8_unicode_ci', 255, function ($column) {
return $this->isStringTypeWithLength($column) && $column['type_brackets'] == 191;
});
}
/**
* Change the database referred to by the connection (null is the default connection) to the provided character set
* (e.g. utf8mb4) and collation (e.g. utf8mb4_unicode_ci). It may be necessary to change the length of some fixed
* length columns such as char and varchar to work with the new encoding. In which case the new length of such
* columns and a callback to determine whether or not that particular column should be altered may be provided. If a
* connection other than the default connection is to be changed, the string referring to the connection may be
* provided as the last parameter (This string will be passed to DB::connection(...) to retrieve an instance of that
* connection).
*
* @param string $charset
* @param string $collation
* @param null|int $newColumnLength
* @param Closure|null $columnLengthCallback
* @param string|null $connection
*/
protected function changeDatabaseCharacterSetAndCollation($charset, $collation, $newColumnLength = null, $columnLengthCallback = null, $connection = null)
{
$tables = $this->getTables($connection);
foreach ($tables as $table) {
$this->updateColumnsInTable($table, $charset, $collation, $newColumnLength, $columnLengthCallback, $connection);
$this->convertTableCharacterSetAndCollation($table, $charset, $collation, $connection);
}
$this->alterDatabaseCharacterSetAndCollation($charset, $collation, $connection);
}
/**
* Get an instance of the database connection provided with an optional string referring to the connection. This
* should be null if referring to the default connection.
*
* @param string|null $connection
*
* @return \Illuminate\Database\Connection
*/
protected function getDatabaseConnection($connection = null)
{
return DB::connection($connection);
}
/**
* Get a list of tables on the provided connection.
*
* @param null $connection
*
* @return array
*/
protected function getTables($connection = null)
{
$tables = [];
$results = $this->getDatabaseConnection($connection)->select('SHOW TABLES');
foreach ($results as $result) {
foreach ($result as $key => $value) {
$tables[] = $value;
break;
}
}
return $tables;
}
/**
* Given a stdClass representing the column, extract the required information in a more accessible format. The array
* returned will contain the field name, the type of field (Without the length), the length where applicable (or
* null), true/false indicating the column allowing null values and the default value.
*
* @param stdClass $column
*
* @return array
*/
protected function extractInformationFromColumn($column)
{
$type = $column->Type;
$typeBrackets = null;
$typeEnd = null;
if (preg_match('/^([a-z]+)(?:\\(([^\\)]+?)\\))?(.*)/i', $type, $matches)) {
$type = strtolower(trim($matches[1]));
if (isset($matches[2])) {
$typeBrackets = trim($matches[2]);
}
if (isset($matches[3])) {
$typeEnd = trim($matches[3]);
}
}
return [
'field' => $column->Field,
'type' => $type,
'type_brackets' => $typeBrackets,
'type_end' => $typeEnd,
'null' => strtolower($column->Null) == 'yes',
'default' => $column->Default,
'charset' => is_string($column->Collation) && ($pos = strpos($column->Collation, '_')) !== false ? substr($column->Collation, 0, $pos) : null,
'collation' => $column->Collation
];
}
/**
* Tell if the provided column is a string/character type and needs to have it's charset/collation changed.
*
* @param string $column
*
* @return bool
*/
protected function isStringType($column)
{
return in_array(strtolower($column['type']), ['char', 'varchar', 'tinytext', 'text', 'mediumtext', 'longtext', 'enum', 'set']);
}
/**
* Tell if the provided column is a string/character type with a length.
*
* @param string $column
*
* @return bool
*/
protected function isStringTypeWithLength($column)
{
return in_array(strtolower($column['type']), ['char', 'varchar']);
}
/**
* Update all of the string/character columns in the database to be the new collation. Additionally, modify the
* lengths of those columns that have them to be the newLength provided, when the shouldUpdateLength callback passed
* returns true.
*
* @param string $table
* @param string $charset
* @param string $collation
* @param int|null $newLength
* @param Closure|null $shouldUpdateLength
* @param string|null $connection
*/
protected function updateColumnsInTable($table, $charset, $collation, $newLength = null, Closure $shouldUpdateLength = null, $connection = null)
{
$columnsToChange = [];
foreach ($this->getColumnsFromTable($table, $connection) as $column) {
$column = $this->extractInformationFromColumn($column);
if ($this->isStringType($column)) {
$sql = "CHANGE `%field%` `%field%` %type%%brackets% CHARACTER SET %charset% COLLATE %collation% %null% %default%";
$search = ['%field%', '%type%', '%brackets%', '%charset%', '%collation%', '%null%', '%default%'];
$replace = [
$column['field'],
$column['type'],
$column['type_brackets'] ? '(' . $column['type_brackets'] . ')' : '',
$charset,
$collation,
$column['null'] ? 'NULL' : 'NOT NULL',
is_null($column['default']) ? ($column['null'] ? 'DEFAULT NULL' : '') : 'DEFAULT \'' . $column['default'] . '\''
];
if ($this->isStringTypeWithLength($column) && $shouldUpdateLength($column) && is_int($newLength) && $newLength > 0) {
$replace[2] = '(' . $newLength . ')';
}
$columnsToChange[] = trim(str_replace($search, $replace, $sql));
}
}
if (count($columnsToChange) > 0) {
$query = "ALTER TABLE `{$table}` " . implode(', ', $columnsToChange);
$this->getDatabaseConnection($connection)->update($query);
}
}
/**
* Get a list of all the columns for the provided table. Returns an array of stdClass objects.
*
* @param string $table
* @param string|null $connection
*
* @return array
*/
protected function getColumnsFromTable($table, $connection = null)
{
return $this->getDatabaseConnection($connection)->select('SHOW FULL COLUMNS FROM ' . $table);
}
/**
* Convert a table's character set and collation.
*
* @param string $table
* @param string $charset
* @param string $collation
* @param string|null $connection
*/
protected function convertTableCharacterSetAndCollation($table, $charset, $collation, $connection = null)
{
$query = "ALTER TABLE {$table} CONVERT TO CHARACTER SET {$charset} COLLATE {$collation}";
$this->getDatabaseConnection($connection)->update($query);
$query = "ALTER TABLE {$table} DEFAULT CHARACTER SET {$charset} COLLATE {$collation}";
$this->getDatabaseConnection($connection)->update($query);
}
/**
* Change the entire database's (The database represented by the connection) character set and collation.
*
* # Note: This must be done with the unprepared method, as PDO complains that the ALTER DATABASE command is not yet
* supported as a prepared statement.
*
* @param string $charset
* @param string $collation
* @param string|null $connection
*/
protected function alterDatabaseCharacterSetAndCollation($charset, $collation, $connection = null)
{
$database = $this->getDatabaseConnection($connection)->getDatabaseName();
$query = "ALTER DATABASE {$database} CHARACTER SET {$charset} COLLATE {$collation}";
$this->getDatabaseConnection($connection)->unprepared($query);
}
}
请在运行此之前请备份您的数据库。使用风险自负！
答案 1 :(得分：1)
数据库字符集和排序规则是新创建的表的默认。 表设置是列的默认设置。
为每张桌子执行此操作：
ALTER TABLE table_name CONVERT TO utf8mb4;